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The Academy's Evolution Site Biological evolution is one of the most central concepts in biology. The Academies have long been involved in helping those interested in science understand the concept of evolution and how it influences all areas of scientific research. This site offers a variety of resources for teachers, students as well as general readers about evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD. Tree of Life The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It also has many practical applications, such as providing a framework to understand the history of species and how they respond to changing environmental conditions. The first attempts to depict the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of various parts of living organisms or small DNA fragments, significantly increased the variety that could be included in a tree of life2. The trees are mostly composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4. Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees by using molecular methods like the small-subunit ribosomal gene. The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only found in a single specimen5. A recent study of all genomes that are known has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and whose diversity is poorly understood6. This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if certain habitats need special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to enhancing crops. This information is also extremely valuable for conservation efforts. It can help biologists identify areas most likely to be home to species that are cryptic, which could have vital metabolic functions and be vulnerable to the effects of human activity. While funds to protect biodiversity are important, the best method to protect the biodiversity of the world is to equip more people in developing nations with the necessary knowledge to act locally and support conservation. Phylogeny A phylogeny, also called an evolutionary tree, reveals the relationships between various groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree which illustrates the evolution of taxonomic categories. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits could be either homologous or analogous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar but do not have the identical origins. Scientists put similar traits into a grouping known as a clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. A phylogenetic tree is constructed by connecting clades to determine the organisms who are the closest to each other. Scientists use molecular DNA or RNA data to build a phylogenetic chart that is more precise and precise. This data is more precise than morphological data and provides evidence of the evolutionary history of an individual or group. Molecular data allows researchers to identify the number of organisms that have a common ancestor and to estimate their evolutionary age. The phylogenetic relationship can be affected by a variety of factors, including the phenotypic plasticity. This is a type of behaviour that can change due to particular environmental conditions. This can make a trait appear more resembling to one species than another and obscure the phylogenetic signals. However, this problem can be reduced by the use of methods like cladistics, which incorporate a combination of analogous and homologous features into the tree. In addition, phylogenetics can aid in predicting the length and speed of speciation. click the following article can help conservation biologists make decisions about which species to protect from extinction. Ultimately, it is the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem. Evolutionary Theory The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been developed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that can be passed on to the offspring. In the 1930s and 1940s, theories from various areas, including genetics, natural selection, and particulate inheritance, merged to form a modern theorizing of evolution. This defines how evolution occurs by the variation in genes within the population, and how these variations change over time as a result of natural selection. This model, which includes genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described mathematically. Recent developments in the field of evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction, and even migration between populations. These processes, as well as other ones like directional selection and gene erosion (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in an individual). Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a study by Grunspan and co. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more information on how to teach evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education. Evolution in Action Traditionally scientists have studied evolution by studying fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process happening in the present. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications and animals alter their behavior to a changing planet. The results are usually easy to see. It wasn't until late 1980s that biologists began to realize that natural selection was also at work. The key is that different traits confer different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next. In the past, if one allele – the genetic sequence that determines colour – appeared in a population of organisms that interbred, it could become more prevalent than any other allele. As time passes, that could mean the number of black moths within a particular population could rise. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. Monitoring evolutionary changes in action is much easier when a species has a rapid generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population were taken frequently and more than 50,000 generations of E.coli have passed. Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also proves that evolution takes time, a fact that some are unable to accept. Another example of microevolution is the way mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are employed. This is due to pesticides causing a selective pressure which favors individuals who have resistant genotypes. The rapidity of evolution has led to an increasing recognition of its importance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding the evolution process can assist you in making better choices about the future of our planet and its inhabitants.